Reproductive Strategies and Colonizing Ability of Two Sympatric Epiphytic Bromeliads in a Tropical Premontane Area

Abstract

Predispersal characteristics that affect the reproductive success in plants may influence their colonizing ability. We evaluated this hypothesis in two sympatric epiphytic bromeliads in Costa Rica, Guzmania monostachia and Tillandsia fasciculata, that show contrasting levels of local seedling recruitment. Genets of G. monostachia, the species with higher recruitment, may reach the reproductive stage faster because of a higher growth rate (6 vs. 13 yr). In addition, in established genets, new asexual ramets develop and reproduce annually, whereas in T. fasciculata, the slower offshoot development implies at least 3 yr to disperse a new batch of seeds. A higher and more continuous seed production in G. monostachia is possible because of a shorter time from flowering to seed dispersal (8–9 vs. 16–20 mo), along with the production of more flowers (29 vs. 22) and naturally pollinated fruits per inflorescence (89% vs. 79% fruit set) and more seeds per fruit (321 vs. 240). Both species showed a high occurrence of spontaneous autogamy that matched the highly selfing condition estimated using microsatellite markers. In all, G. monostachia displayed the reproductive traits of a pioneer species. Here, we emphasize the importance of seed availability in determining the population and community structure of epiphytic bromeliads in secondary and mature forests, along with factors affecting dispersal and plant survival.